When producing an image of a patient with the help of a medical imaging procedure, a respective position of the patient is normally noted. Known imaging procedures are, for example, classical projection radiography, computer tomography, magnetic resonance tomography or imaging based on ultrasound. Depending on the imaging procedure used, the image is available, for example, in the form of a projection image, a cross-section or a 3D image. With a digital image, the respective position of the patient is normally saved with the digital image as additional information. According to the standard for “Digital Imaging and Communications in Medicine”, DICOM for short, at least three different specifications are provided for the patient position: the “Patient Orientation” according to tag 0020,0020, the “Patient Position” according to tag 0018,5100 and the “View Position” according to tag 0018,5101.
DICOM is a standard of the “National Electrical Manufacturers Association”, NEMA for short, and more information can be obtained at the DICOM internet site http:\\medical.nema.org\.
The “Patient Orientation” defines the position of the patient relative to the focal planes of the respective image and is the result of a concatenation of two parts, whereby the first part specifies the direction of the image lines from left to right, and the second part specifies the direction of the image columns from top to bottom. Six basic directions are provided for the indication of each part: “Head” in the direction of the head of the patient, “Feet” in the direction of the feet, “Anterior” in the direction of the front side of the body, “Posterior” in the direction of the back side of the body, “Right” in the direction of the right side of the body and “Left” in the direction of the left side of the body. The corresponding body directions for body parts are derived from the definitions provided above, whereby a patient standing upright forms the basis, whose arms are located on the respective side of the body, and whose hands opened flat point forward with their inner surfaces. The respective basic directions are normally abbreviated with their respective first letters. If the image lines or the image columns are not aligned primarily with a basic direction, then the respective part of the “Patient Orientation” contains direction information in the form of a concatenation of at least two of the basic directions in which the image lines or image columns point.
The “Patient Position” defines the position of the patient relative to the imaging device with which the respective image is created, and is the result of a concatenation of two parts. “Head First” (HF) is entered in the first part if the head of the patient points to the front side of the imaging device, and “Feet First” (FF) if the feet of the patient point to the front side of the imaging device. One of the following specifications is entered in the second part of the “Patient Position”: “Supine” (S) if the face of the patient points upwards, “Prone” (P) if the face of the patient points downwards, “Decubitus Left” (DL) if the left side of the patient points downwards, and “Decubitus Right” (DR) if the right side of the patient points downwards.
For a radiographic imaging procedure, the “View Position” defines the position of the patient with respect to the radiographic line of sight, i.e. the direction from which the X-ray radiation traverses through the body of the patient. The “View Position” consists of only one single part, in which the following information can be entered: “Anterior/Posterior” (AP) if the X-ray radiation traverses through the front side of the body towards the back of the body of the patient, “Posterior/Anterior” (PA) if the X-ray radiation traverses through the back side of the body towards the front of the body of the patient, “Left Lateral” (LL) if the X-ray radiation traverses through the right side of the body towards the left of the body of the patient, “Right Lateral” (RL) if the X-ray radiation traverses through the left side of the body towards the right of the body of the patient. For mixed information for the four entries specified above, the additional four entries “Right Lateral Decubitus” (RLD), “Left Lateral Decubitus” (LLD), “Right Lateral Oblique” (RLO) and “Left Lateral Oblique” (LLO) are provided.
Additional notes on the definition described above for the position of the patient according to the DICOM standard can be gathered from the documentation previously mentioned for this standard. In addition to the definition of the position of the patient according to the DICOM standard, additional definitions are generally known, which are at least partially comparable to the DICOM standard.
For currently common imaging devices, their respective operator must know the respective position of the patient and make note of the respective image of the patient. For an imaging device for the creation of digital images, it is often provided that the respective position of the patient is to be entered by means of an operating console of the imaging device or a computer associated with the respective imaging device. The identification of the respective position of the patient as well as the subsequent entry of the patient position are time-consuming for the operator and can lead to erroneous entries. On the one hand, this leads to the obstruction of the workflow when creating images, and on the other hand, this leads to a possible erroneous diagnosis as a result of an erroneously noted position of the patient. The respective image of the patient is not always identifiable on the basis of the respective image, so, for example, the risk exists that the position of a patient whose heart is located in the right side of the chest is erroneously identified on the basis of a frontal X-ray image of the chest.
From DE 19912708A1 a method and a device for the control of the positioning of an object to be irradiated in the radiation field of an irradiation device is known, whereby at least one partial cross-section or one partial volume data set for the total irradiated volume is included; the actual position of the object relative to the radiation field is determined based on the cross-section recorded. In fact, this allows a type of direct online position control for the correction of a possible erroneous positioning, but does not solve the problem that an identification of the position of the patient based on an X-ray image that is created with X-ray radiation penetrating the body of the patient is prone to errors.